Make contenteditable="false" element as atomic node for selection motion

LayoutTests/editing/selection/resources/js-test-selection-shared.js

+function $(id) { return document.getElementById(id); }
+
+var selection= window.getSelection();
+
+function testCaretMotion(param) {
+    var direction = param.direction;
+    var granularity = param.granularity;
+    var repeatCount = param.repeatCount || 1;
+    var origin = param.origin;
+    var originOffset = param.originOffset || 0;
+    var target = param.target;
+    var targetOffset = param.targetOffset || 0;
+
+    if (direction == 'both') {
+        testCaretMotion({
+            'direction': 'forward',
+            'granularity': granularity,
+            'repeatCount': repeatCount,
+            'origin': origin,
+            'originOffset': originOffset,
+            'target': target,
+            'targetOffset': targetOffset
+        });
+        testCaretMotion({
+            'direction': 'backward',
+            'granularity': granularity,
+            'repeatCount': repeatCount,
+            'origin': target,
+            'originOffset': targetOffset,
+            'target': origin,
+            'targetOffset': originOffset
+        });
+        return;
+    }
+
+    if (typeof origin == 'string')
+        origin = $(origin);
+
+    if (typeof target == 'string')
+        target = $(target);
+
+    if (originOffset < 0)
+        originOffset = origin.firstChild.length + originOffset + 1;
+
+    if (targetOffset < 0)
+        targetOffset = target.firstChild.length + targetOffset + 1;
+
+    selection.setPosition(origin.firstChild, originOffset);
+    debug('Move ' + direction + ' ' + granularity + ' x ' + repeatCount);
+    for (var i = 0; i < repeatCount; ++i)
+        selection.modify("move", direction, granularity);
+    shouldEvaluateTo('selection.anchorNode', target.firstChild);
+    shouldEvaluateTo('selection.anchorOffset', targetOffset);
+}
+
 function objectAsString(object, properties) {
     var result = "[";
     for (var x = 0; x < properties.length; x++) {
         var property = properties[x];
         if (x != 0)
             result += " ";
 
         var value = object[property];
         if (value && value.nodeType) // textNode
             value = value + "(" + value.nodeValue + ")";
@@ skipping 28 matching lines @@
 }
 
 function clickAt(x, y) {
     if (window.eventSender) {
         eventSender.mouseMoveTo(x, y);
         eventSender.mouseDown();
         eventSender.mouseUp();
         return true;
     }
 }